Bearing seal means for an electrically driven fan

ABSTRACT

A tubular ferrule connects the fan impeller to the rotor of the fan motor. Fixed within the ferrule is a porous bearing rotatable about a shaft fixed to the fan frame. One end of the ferrule carries a cuplike member, within which may be a felt ring, for accumulating any lubricating oil seeping out from between the bearing and shaft.

ited States Patent Karl E. Friese Dover, NB.

Jan. 9, 1970 Oct. 19, 1971 IMC Magnetics Corporation inventor Appl. No.Filed Patented Assignee BEARING SEAL MEANS FOR AN ELECTRICALLY DRIVENFAN 7 Claims, 4 Drawing Figs.

US. Cl 416/174,

416/244, 308/364, 416/170 Int. Cl ..F04d 29/04, F16c 1/29 Field ofSearch 416/3, 170,

[56] References Cited UNITED STATES PATENTS 3,167,672 1/1965 Tupper...310/90 3,378,192 4/1968 Friese 417/353 Primary Examiner-Martin P.Schwadron Assistant ExaminerClemens Schirnikowski Attorney-Breitenfeld &Levine ABSTRACT: A tubular ferrule connects the fan impeller to therotor of the fan motor. Fixed within the ferrule is a porous bearingrotatable about a shaft fixed to the fan frame. One end of the ferrulecarries a cuplike member, within which may be a felt ring, foraccumulating any lubricating oil seeping out from between the bearingand shaft.

BEARING SEAL MEANS FOR AN ELECTRICALLY DRIVEN FAN This invention relatesto electrically driven fans of the type shown in U.S Pat. No. 3,378,192,wherein the annular rotor of the fan motor is rotatably mounted withrespect to a stationary shaft, projecting from the fan framework, bymeans of a ferrule anda bearing concentrically arranged within therotor, the fan impeller being secured to the ferrule.

More particularly, the invention relates to the sealing means at one endof the bearing.

In these fans, the ferrule has an enlarged head at one end accommodatinga source of lubricating oil, and oil is drawn from this source betweenthe relatively moving opposed surfaces of the bearing and shaft. Some ofthe oil flows toward the opposite end of the bearing, and tends to seepout from between that end and the shaft.

It is an object of the present invention to provide a sealing means ofsimple construction for accumulating any oil which seeps past one end ofthe bearing.

It is another object to provide such a sealing means which has norubbing contact with any surface and hence is not subject to wear.

It is a further object to provide a sealing means capable of feedingaccumulated oil back to the bearing when needed.

To achieve these objectives, the end of the ferrule opposite theenlarged head carries an annular cuplike means surrounding the shaft.The inner edge of the cuplike means is slightly spaced from both theshaft and the end of the bearing, the relative spacing being such thatwhen an oil droplet moves past the bearing, it engages the rotatinginner edge of the cup and is thrown into the cup. A felt ring within thecup absorbs the oil, and when the bearing becomes dry the oil in thering is fed back to the bearing.

Additional features and advantages of the invention will be brought outin the following description in which reference is made to theaccompanying drawings.

In the drawings:

FIG. 1 is a front elevational view of a fan of the type to which thisinvention relates;

FIG. 2 is a vertical cross-sectional view taken on line 2-2 of FIG. 1,

FIG. 3 is a fragmentary vertical cross-sectional view, on an enlargedscale, taken on line 3-3 of FIG. 1; and

FIG. 4 is an elevational view partially in section, of a ferruleaccording to this invention.

The fan chosen to illustrate this invention includes a frame comprisinga square outer portion provided with a central circular opening 11, anda motor support 12 held at the center of the opening 11 by a number ofstruts 13 extending between the support 12 and the outer portion of theframe. If desired, the entire frame can be formed as a single casting.At its corners, the frame 10 is provided with holes 14 for accommodatingsuitable fasteners (not shown). By means of these fasteners, the framecan be mounted in or near a region in which air is to be circulated.

The motor support 12 is a circular, cuplike element having a centralbore 15. One end of a stationary generally cylindrical shaft 18 is fixedin the bore 15, by any suitable means such as a cement, and the balanceof the shaft 18 projects from the sup port 12 in cantilever fashion. Theshaft, in effect, serves as an extension of the frame 10 upon which theimpeller of the fan is rotatably supported.

The impeller is rotated by an induction motor comprising a stator 20 anda rotor 21. The stator 20 is a generally annularshaped body having acentral bore 22, and is fixed within the motor support 12 by suitablefastening means (not shown). The stator is provided with the usual fieldwindings 25 which may be energized from any suitable. source ofelectrical current. The rotor 21 is an annular body located within thebore 22 of the stator, but unconnected to the stator.

The impeller of the fan may comprise a generally cupshaped hub 26 formedwith radially projecting blades 27. At the center of its front wall, thehub presents an inwardly projecting collar 28. Preferably, the hub 26,blades 27, and collar 28 are integrally formed of, for example, asuitable molded plastic. When the impeller is in place, as shown in FIG.2, the sidewalls of the hub 26 terminate close to the sidewalls of themotor support 12, whereby the hub and motor support form a housing forthe induction motor.

The impeller is secured to the rotor 21 by means of a generally tubularferrule 29, the body portion of the ferrule being fixed, such as by asuitable cement, to the inner surface of the rotor. The ferrule extendsbeyond the rotor, and terminates in a head 30 of enlarged diameter. Aflange 31 extends radially outwardly from the free end of the head 30.The outer diameter of the head 30 is about equal to the inner diameterof the collar 28, and the head 30 is formed with axially extendingridges 34 which project. radially from its outer surface. Thus, when theferrule head 30 is forced into the collar 28, the ridges 34 grip theinner surface of the collar and secure the ferrule to the impeller.Thereafter, the body of the ferrule is secured to the rotor 21. Theflange 31 defines the assembled relationship of the ferrule andimpeller, by seating against the outer face of the hub 26.

Fixed to the inner surface of the body of the ferrule 29 is acylindrical bearing 35 which is rotatable over the surface of the shaft18. By means of this bearing, the ferrule, and hence the rotor 21 andthe impeller are rotatably supported on the shaft 18.

In assembling the fan, the stator is first fixed to the framework. Thebearing, ferrule, rotor, impeller assembly is then slipped over theshaft 18, and a snap ring 36 and spacer washers 37 are then pushed overthe end 44 of the shaft 14, the ring 36 snapping into an annular groovenear the shaft end. The washers 37 abut against the right end face (inFIG. 3) of the bearing 35 and thereby prevent the ferrule 29 and theparts fixed to it from moving toward the right and slipping off theshaft 18. Snugly fitted within the ferrule head 30 is a cap 38 enclosinga fibrous ring 39, a fibrous disk 40, and a nylon disk 41. Adjacent tothe outer face of the cap 38, the inner surface of the wall of theferrule head is formed with an annular groove 42 accommodating a snapring 43. A washer 45 is located between the snap ring 43 and the cup 38.As a consequence of this construction, when the fan is in operation andblowing air toward the right in FIGS. 2 and 3, the reaction force on theimpeller urges the latter toward the left. This force is transmittedthrough the ferrule, snap ring 43 and washer 45, to the cap 38, which intum forces the nylon disk 41 against the rounded end 44 of the shaft.Movement of the rotating parts toward the left is thereby limited.

The bearing is formed of a very porous material, such as produced bysintering a mixture of graphite and bronze powder. Before assembly withthe other parts, the bearing is saturated throughout with a lubricantsuch as oil. The fibrous ring 39 and disk 40, which may be formed offelt, are also saturated with oil and serve as a reservoir of lubricantfor the bearing.

At its end opposite head 30, the ferrule 29 is reversely turned inwardlyto define an annular cuplike means 48 surrounding shaft 18. Although cup48 is shown integral with the remainder of ferrule 29, it could be aseparate piece secured to the ferrule, as by cement. The cup 48 extendsbeyond the end 49 of bearing 35, and serves as a seal for trapping anyoil which flows out from between the end 49 of the bearing and the shaft18. Preferably a fibrous ring 50, which may be felt, is located withincup 48 for absorbing oil entering the cup.

The radially inner wall 52 of annular cup 48 is spaced slightly fromshaft 18, and the inner free edge 51 at the inner end of wall 52 isspaced from the end 49 of bearing 35. The space 53 between wall 52 andshaft 18 is of a capillary nature, e.g., of the order of 0.005 inch, sothat oil will not readily flow through the space. The space 54 betweenedge 51 and the end face of bearing 35 may be about the same size asthat of space 53, but preferably is slightly larger. In any case, space54 should not be larger than about 0.010 inch.

Should a drop of oil seep out from between the end 49 of bearing 35 andthe shaft 18, it will contact inner edge 51 of cup 48. Since this edgeis rotating rapidly, the oil drop is thrown radially outwardly bycentrifugal force into cup 48, wherein it is absorbed by ring 50. Thus,the oil gets no opportunity to flow past edge 51, toward the left inFIG. 3, between wall 52 and shaft 18.

As absorbent ring 50 accumulates oil, it becomes a reservoir of oil. Intime, the oil within bearing 35 tends to evaporate and break down, untileventually bearing 35 requires oil. Since the bearing is in contact withthe ring 50, the porous bearing will I suck oil out of the ring.

The major lubrication for the bearing is of course made available by theoil within ring 39 and disk 40. In order to add oil to the assembly, anoil-filled hypodermic syringe may be used. The syringe is pushed througha hole 55 in cup 38 and into disk 40.

The invention has been shown and described in preferred form only, andby way of example, and many variations may be made in the inventionwhich will still be comprised within its spirit. It is understood,therefore, that the invention is not limited to any specific form orembodiment except insofar as such limitations are included in theappended claims.

lclaim:

1. An electrically driven fan comprising:

a frame an induction motor having a stator fixed to said frame and w anannular-shaped rotor rotatable with respect to said stator and frame,

a stationary shaft fixed at one end to said frame and projecting incantilever fashion therefrom,

a hollow, generally cylindrical ferrule fixed within said rotor androtatable therewith,

a cylindrical bearing fixed within said ferrule and rotatable withrespect to said shaft, said rotor, ferrule, and bearing being rotatedtogether when said motor is energized,

a fan impeller fixed to said ferrule, and

annular cuplike means carried by one end of said ferrule and rotatabletherewith, said cuplike means extending beyond one end of said bearingand surrounding said shaft, the inner edge of said cuplike means closestto said bearing being spaced slightly from both said shaft and saidbearing, said one end of said bearing communicating with the interior ofsaid cuplike means through said spacing between said cup edge and saidbearing end, whereby if a drop of oil lubricating the relatively movingshaft and bearing surfaces seeps past said one end of said bearing itwill contact said inner edge of said cuplike means and be thrownradially outwardly by centrifugal force through said spacing betweensaid cup edge and said bearing end and into said cuplike means.

2. A fan as defined in claim 1 wherein the spacing between said inneredge and said bearing is larger than the spacing between said inner edgeand said shaft.

3. A fan as defined in claim 2 wherein the spacing between said inneredge and said shaft is of the order of 0.005 inch.

4. A fan as defined in claim 2 wherein the spacing between said inneredge and said one end of said bearing is no more than about 0.010 inch.

5. A fan as defined in claim 1 wherein said cuplike means is integralwith said ferrule.

6. A fan as defined in claim 1 including a ring of absorptive materialwithin said cuplike means.

7. A fan as defined in claim 6 wherein said absorptive material is felt.

1. An electrically driven fan comprising: a frame an induction motorhaving a stator fixed to said frame and an annular-shaped rotorrotatable with respect to said stator and frame, a stationary shaftfixed at one end to said frame and projecting in cantilever fashiontherefrom, a hollow, generally cylindrical ferrule fixed within saidrotor and rotatable therewith, a cylindrical bearing fixed within saidferrule and rotatable with respect to said shaft, said rotor, ferrule,and bearing being rotated together when said motor is energized, a fanimpeller fixed to said ferrule, and annular cuplike means carried by oneend of said ferrule and rotatable therewith, said cuplike meansextending beyond one end of said bearing and surrounding said shaft, theinner edge of said cuplike means closest to said bearing being spacedslightly from both said shaft and said bearing, said one end of saidbearing communicating with the interior of said cuplike means throughsaid spacing between said cup edge and said bearing end, whereby if adrop of oil lubricating the relatively moving shaft and bearing surfacesseeps past said one end of said bearing it will contact said inner edgeof said cuplike means and be thrown radially outwardly by centrifugalforce through said spacing between said cup edge and said bearing endand into said cuplike means.
 2. A fan as defined in claim 1 wherein thespacing between said inner edge and said bearing is larger than thespacing between said inner edge and said shaft.
 3. A fan as defined inclaim 2 wherein the spacing between said inner edGe and said shaft is ofthe order of 0.005 inch.
 4. A fan as defined in claim 2 wherein thespacing between said inner edge and said one end of said bearing is nomore than about 0.010 inch.
 5. A fan as defined in claim 1 wherein saidcuplike means is integral with said ferrule.
 6. A fan as defined inclaim 1 including a ring of absorptive material within said cuplikemeans.
 7. A fan as defined in claim 6 wherein said absorptive materialis felt.